The concentration of planet-heating pollutants clogging the atmosphere hit record levels in 2023, the World Meteorological Organization (WMO) has said.
It found carbon dioxide (CO2) is accumulating faster than at any time in human history, with concentrations having risen by more than 10% in just two decades.
The increase was driven by humanity’s “stubbornly high” burning of fossil fuels, the WMO found, and made worse by big wildfires and a possible drop in the ability of trees to absorb carbon.
The concentration of CO2 reached 420 parts per million (ppm) in 2023, the scientists observed. The level of pollution is 51% greater than before the Industrial Revolution, when people began to burn large amounts of coal, oil and fossil gas.
Concentrations of strong but short-lived pollutants also surged. Methane concentrations hit 1,934 parts per billion (ppb), a rise of 165% from preindustrial levels, and nitrous oxide hit 336.9 parts per billion (ppb), a rise of 25%.
Burning fossil fuels – such as the petrol to power a car or the coal to feed a thermal power plant – releases gases that trap sunlight and heat the planet.
The WMO announcement comes ahead of the COP29 climate summit in Azerbaijan next month. It follows a report from the UN Environment Programme on Thursday that found the world is on track to heat 3˚C by the end of the century.